The Program in Nucleic Acid Biology focuses on mechanisms underlying DNA replication and mutagenesis as well as on the post-transcriptional regulation of gene expression by processes such as alternative splicing and microRNA function. The Program includes basic researchers interested in cell transformation and cancer who focus their work on a wide range of interrelated topics, including human genetics, DNA replication and repair, mRNA transcription and processing and gene regulation by endogenous or introduced non-coding RNAs. Program members share a common interest in the role of protein:nucleic acid interactions in regulating gene expression and cell growth. Although there is a significant interest in using prokaryotic model systems, the primary focus is on eukaryotic cells. Members interact through regularly scheduled research presentations, such as those sponsored by the Duke Center for RNA Biology, and through a wide range of relevant seminar presentations. Collaborations between members of the program, and particularly with other Cancer Center members, are numerous and productive. A new initiative relates to efforts to use RNA interference (RNAi) to study the role of specific viral and cellular gene products in the regulation of cell growth and transformation as well as to study the potentially critical role of the large endogenous family of non-coding RNA, termed microRNAs, in these processes. Co-leaders of the Program are Bryan R. Cullen, James B. Duke Professor of Molecular Genetics and Microbiology, and Mariano Garcia- Blanco, Professor of Molecular Genetics and Microbiology. The Program includes 21 members from 7 basic and clinical departments within Duke University.